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J. Klikovits:
"Oxidation of low-index and vicinal Rh and Pd surfaces";
Vortrag: Seminar Institut für Allgemeine Physik (IAP), TU Wien; 23.01.2007.

We have studied the oxidation of low-index and vicinal Rh and Pd surfaces. Two-dimensional oxide formation on (111) surfaces of Rh and Pd will be described. Exposing the vicinal surfaces of these two metals to oxygen leads to variation of the step width, depending on oxidizing conditions. In the case of Rh(223) we report three different regimes at rather mildly oxidizing conditions, including formation of a one-dimensional oxide at the steps. Comparing the present results with our previous study of Rh(553) nicely demonstrates the different oxidation behavior of the two types of microfacets on (111) surfaces. In both cases, Rh-Rh distances in the step are expanded, matching the atomic distances within the two-dimensional oxide on Rh(111). Further oxidation leads to step bunching and formation of large (111) terraces, covered by the two-dimensional Rh(111) oxide.
Oxygen exposure to vicinal Pd(553) leads to terrace expansion by one atom row to adapt to the surface oxide structure. Further oxidation again leads to two-dimensional oxide formation on (111) facets. Our studies show that instability of vicinal surfaces under the influence of an adsorbate is rather common and we present different mechanisms of oxygen-induced step bunching.